De-normalization for performance tuning

Do we use de-normalization for performance tuning. If so, can someone provide me a good example how it helps.

Appreciate your help
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rather than joining data from 2 or more tables,  you simply read data from one larger table.

less io,  less cpu , less temp space for sorting/hashing, etc.

downside is the updating of the data within denormalized sets.  That's why they are typically used for reporting purposes, and not transactional storage
example, using the standard SCOTT example schema


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You could also check this article: "The Dangerous Illusion: Denormalization, Performance and Integrity"

d27m11yAuthor Commented:
why the B?  what was missing/wrong?

if you needed more info, please ask before assigning penalty grades
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